ronja(reasonable optical near joint access) report
TRANSCRIPT
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RONJA
(Reasonable Optical Near Joint Access)
A Seminar Report
Submitted by
RAGHAVENDRA.S.RAO
in partial ful fi lment for the award of the degree
of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND TELECOMMUNICATION
Guided by
Mr. B.B.WATTAMWAR
At
MAHARASHTRA INSTITUTE OF TECHNOLOGY
AURANGABAD
2013-14
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CERTIFICATE
This is to certify that, the report RONJA (Reasonable Optical Near Joint Access)
submitted by
Raghavendra.S.Rao
is a bonafide work completed under my supervision and guidance in partial fulfilment for
award of Bachelor Of Technology (Electronics and Telecommunication) Degree of
Maharashtra Institute Of Technology Aurangabad.
Place : Aurangabad
Date :
Dr. S. P. Bhosle
Principal
Maharashtra Institute Of Technology Aurangabad
Mr. B.B.Wattamwar
Guide
Mrs. V. M. Kulkarni
Head of the Department
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TABLE OF CONTENTS
CHAPTER TITLE PAGE
ABSTRACT 4
ACKNOWLEDGMENT
LIST OF ABBREVIATIONS
5
6
I INTRODUCTION
1.1 Introduction 7
1.2 Necessity and objectives 8
1.3 Theme and Organisation 9
II LITERATURE SURVEY
2.1 Point-to-Point Protocol (PPP) 10
2.2 Free Space Vs Radio 13
2.3 Optics 14
2.4 Signals 15
2.5 LED Vs Laser 24
III SYSTEM DEVELOPMENT
3.1 General Scrutiny 26
3.2 Block diagram and its Description
3.3 Models and their specifications
28
39
IV CONCLUSION
4.1 Applications and Future Scope 45
4.2 Pros & Cons 47
V REFERENCES 48
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ABSTRACT
RONJA (Reasonable Optical Near Joint Access)Allows one to make a free
space 10Mbps full-duplex Ethernet bridge between two points up to 1.4 km
away using visible incoherent light.
The transmitter sends a signal with a Light Emitting Diode (LED), the light rays
are collimated (paralleled) by a lens. On the other side of the bridge the receiver
uses another lens to focus light onto a photo diode. The Twister is the
electronics that cleans up the signal, adds a pulse when no data is being
communicated, and adds the link integrity pulse back to the Ethernet cable. The
pulse is used to keep the Receiver knowing what a signal is over noise.
This report covers the basic introduction to RONJA, Scrutiny of its system
functioning, advantages of RONJA along with its future improvements and
scopes.
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ACKNOWLEDGEMENT
I wish to express my deep gratitude and appreciation for the invaluable guidance of our
professors throughout the span of preparing this seminar. We are indebted to our college
Principal Dr. S. P. Bhosle.
I am also thankful to our HOD Mrs. V. M. Kulkarni and my Seminar Guide
Mr.B.B.Wattamwar for his precious and elaborate suggestions. Their excellent guidance
made me to complete this task successfully within a short duration.
The inspiration behind the every aspect of life constructs a way to get success, which I
have got from all the professors of the department.
No thanks giving would be complete without mentioning my parents and family
members, without their constant support and encouragement, this assignment wouldnt have
been successful.
RAGHAVENDRA.S.RAO
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LIST OF ABBREVIATIONS
SONET-Synchronous Optical Networking
ISP-Internet Service Provider
NBF-NetBIOS Frames protocol
DECnet-Digital Equipment CorporationNetworks
IPCP-IP Control Protocol
SSl-Secure Sockets Layer
SSH-Secure Shell
L2TP-Layer 2 Tunneling Protocol IEEE-Institute of Electrical and Electronics Engineers
FCC-Federal Communications Commission
ASCII-American Standard Code for Information Interchange
RX-Receiver
TX-Transmitter
PCB-Printed Circuit board
HDLC-High-Level Data Link Control
ADCCP-Advanced Data Communication Control Procedures
LAN-Local Area Network
LLC-Logical Link Control
MAC-Media Access Control
CSMA/MD-Carrier Sense Multiple Access with Collision Detection
http://en.wikipedia.org/wiki/Digital_Equipment_Corporationhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Digital_Equipment_Corporation -
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INTRODUCTION
RONJAis afree-space optical communication system which transmits datawirelessly using
beams oflight.Ronja can be used to create a 10 Mbit/sfull duplexEthernetpoint-to-point
link, having a range of 1.4 km, through an optoelectronic device you can mount on your
house and connect your PC, home or office network with other network.
The device consists of a receiver andtransmitterpipe (optical head) mounted on a sturdy
adjustable holder. Twocoaxial cables are used to connect the rooftop installation with a
protocol translator installed in the house near acomputer orswitch.The range can be
extended to 1.9 km (1.2 mi) by doubling or tripling the transmitter pipe.
A complete RONJA system is made up of 2transceivers:2 opticaltransmitters and 2opticalreceivers.They are assembled individually or as a combination. The complete system
layout is shown in theblock diagram above.
The range of the basic configuration is 1.4 km (0.9 miles).
.
http://en.wikipedia.org/wiki/Free-space_optical_communicationhttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Full_duplexhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Transceivershttp://en.wikipedia.org/wiki/Transmittershttp://en.wikipedia.org/w/index.php?title=Optical_receiver&action=edit&redlink=1http://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/wiki/Block_diagramhttp://en.wikipedia.org/w/index.php?title=Optical_receiver&action=edit&redlink=1http://en.wikipedia.org/wiki/Transmittershttp://en.wikipedia.org/wiki/Transceivershttp://en.wikipedia.org/wiki/Network_switchhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Full_duplexhttp://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Wirelesshttp://en.wikipedia.org/wiki/Free-space_optical_communication -
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NECESSITY AND OBJECTIVES
The Foundation of any Project lies in its need which defines its existence. In Todays Era of
Wireless Communication, there is an emerging trend which appeals the use of optical energy
to transfer information. Moreover, in it, the most efficient, most advantageous and secure
systems are preferred. Ronja is amongst those systems which can easily cater to all these
needs. The Demands of Full Duplex, high Speed, Energy efficient and point-to-point secure
transmission can be efficiently fulfilled by RONJA, thus proving its necessity and Objectives.
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THEME AND ORGANISATION
Ronja has a Theme of Pure Optical Communication in Synergy with Networking, associated
with it. It is all concerned about the transmission and reception of data within the boundaries
defined by its Design and Structural capabilities obeying all the necessary Protocols. Twilight
laboratories, Prague, Czech Republic, is the organization which is associated with RONJA
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LITERTURE SURVEY
Point-to-Point Protocol:
Point-to-Point Protocol (PPP) is adata linkprotocol used to establish a direct connection
between twonodes.It can provide connectionauthentication,transmissionencryption and
compression.
PPP is used over many types of physical networks includingserial cable,phone line,trunk
line,cellular telephone,specialized radio links, and fiber optic links such asSONET.PPP is
also used overInternet access connections.Internet service providers (ISPs) have used PPP
for customerdial-up access to theInternet,since IP packets cannot be transmitted over a
modem line on their own, without some data link protocol. Two derivatives of PPP,Point-to-Point Protocol over Ethernet (PPPoE) andPoint-to-Point Protocol over ATM (PPPoA), are
used most commonly by Internet Service Providers (ISPs) to establish aDigital Subscriber
Line (DSL) Internet service connection with customers.
PPP is commonly used as adata link layerprotocol for connection oversynchronous and
asynchronous circuits,where it has largely superseded the olderSerial Line Internet Protocol
(SLIP) and telephone company mandated standards (such asLink Access Protocol, Balanced
(LAPB) in theX.25protocol suite). The only requirement for PPP is that the circuit provided
beduplex.PPP was designed to work with numerousnetwork layerprotocols, including
Internet Protocol (IP),TRILL,Novell'sInternetwork Packet Exchange (IPX),NBF,DECnet
andAppleTalk.
PPP permits multiple network layer protocols to operate on the same communication link.
For every network layer protocol used, a separate network control protocol (NCP) is provided
in order to encapsulate and negotiate options for the multiple network layer protocols. It
negotiates network-layer information, e.g. network address or compression options, after the
connection has been established.
For example, Internet Protocol (IP) uses the IP Control Protocol (IPCP), and Internetwork
Packet Exchange (IPX) uses the Novell IPX Control Protocol (IPX/SPX). NCPs include
fields containing standardized codes to indicate the network layer protocol type that the PPP
connection encapsulates.
The phases of the Point to Point Protocol according are listed below:
http://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Protocol_%28computing%29http://en.wikipedia.org/wiki/Node_%28networking%29http://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Data_compressionhttp://en.wikipedia.org/wiki/Serial_cablehttp://en.wikipedia.org/wiki/Phone_linehttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Cellular_telephonehttp://en.wikipedia.org/wiki/SONEThttp://en.wikipedia.org/wiki/Internet_accesshttp://en.wikipedia.org/wiki/Internet_service_providerhttp://en.wikipedia.org/wiki/Dial-up_accesshttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_ATMhttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Synchronous_circuithttp://en.wikipedia.org/wiki/Asynchronous_circuithttp://en.wikipedia.org/wiki/Serial_Line_Internet_Protocolhttp://en.wikipedia.org/wiki/LAPBhttp://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/Duplex_%28telecommunications%29http://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/TRILL_%28computing%29http://en.wikipedia.org/wiki/Internetwork_Packet_Exchangehttp://en.wikipedia.org/wiki/NetBIOS_Frames_protocolhttp://en.wikipedia.org/wiki/DECnethttp://en.wikipedia.org/wiki/AppleTalkhttp://en.wikipedia.org/wiki/IPCPhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPX/SPXhttp://en.wikipedia.org/wiki/IPCPhttp://en.wikipedia.org/wiki/AppleTalkhttp://en.wikipedia.org/wiki/DECnethttp://en.wikipedia.org/wiki/NetBIOS_Frames_protocolhttp://en.wikipedia.org/wiki/Internetwork_Packet_Exchangehttp://en.wikipedia.org/wiki/TRILL_%28computing%29http://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Duplex_%28telecommunications%29http://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/LAPBhttp://en.wikipedia.org/wiki/Serial_Line_Internet_Protocolhttp://en.wikipedia.org/wiki/Asynchronous_circuithttp://en.wikipedia.org/wiki/Synchronous_circuithttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Digital_Subscriber_Linehttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_ATMhttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocol_over_Ethernethttp://en.wikipedia.org/wiki/Modemhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Dial-up_accesshttp://en.wikipedia.org/wiki/Internet_service_providerhttp://en.wikipedia.org/wiki/Internet_accesshttp://en.wikipedia.org/wiki/SONEThttp://en.wikipedia.org/wiki/Cellular_telephonehttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Trunkinghttp://en.wikipedia.org/wiki/Phone_linehttp://en.wikipedia.org/wiki/Serial_cablehttp://en.wikipedia.org/wiki/Data_compressionhttp://en.wikipedia.org/wiki/Encryptionhttp://en.wikipedia.org/wiki/Authenticationhttp://en.wikipedia.org/wiki/Node_%28networking%29http://en.wikipedia.org/wiki/Protocol_%28computing%29http://en.wikipedia.org/wiki/Data_Link_Layer -
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Link Dead: This phase occurs when the link fails, or one side has been told to disconnect (e.g.
a user has finished his or her dialup connection.)
Link Establishment Phase: This phase is where Link Control Protocol negotiation is
attempted. If successful, control goes either to the authentication phase or the Network-Layer
Protocol phase, depending on whether authentication is desired.
Authentication Phase: This phase is optional. It allows the sides to authenticate each other
before a connection is established. If successful, control goes to the network-layer protocol
phase.
Network-Layer Protocol Phase: This phase is where each desired protocols'Network Control
Protocols are invoked. For example,IPCP is used in establishing IP service over the line.
Data transport for all protocols which are successfully started with their network control
protocols also occurs in this phase. Closing down of network protocols also occur in this
phase.
Link Termination Phase: This phase closes down this connection. This can happen if there is
an authentication failure, if there are so many checksum errors that the two parties decide to
tear down the link automatically, if the link suddenly fails, or if the user decides to hang up
his connection.
http://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocol_Control_Protocolhttp://en.wikipedia.org/wiki/Internet_Protocol_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocolhttp://en.wikipedia.org/wiki/Network_Control_Protocol -
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Many protocols can be used totunnel data over IP networks. Some of them, likeSSL,SSH,
orL2TP create virtualnetwork interfaces and give the impression of a direct physical
connections between the tunnel endpoints. On aLinux host for example, these interfaces
would be called tun0.
As there are only two endpoints on a tunnel, the tunnel is a point-to-point connection and PPP
is a natural choice as a data link layer protocol between the virtual networks interfaces. PPP
can assign IP addresses to these virtual interfaces, and these IP addresses can be used, for
example, to route between the networks on both sides of the tunnel.
http://en.wikipedia.org/wiki/Tunneling_protocolhttp://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/L2TPhttp://en.wikipedia.org/wiki/Network_interfacehttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Linuxhttp://en.wikipedia.org/wiki/Network_interfacehttp://en.wikipedia.org/wiki/L2TPhttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/Secure_Sockets_Layerhttp://en.wikipedia.org/wiki/Tunneling_protocol -
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Free Space vs. Radio
Radio (Such as IEEE 802.11) can also be used to create a network bridge. Free Space Optics
have some advantages and disadvantages compared to Radio.
1. Eavesdropping
Because of the nature of radio waves, it is harder to contain where the radio waves go, even
in directional point to point networks a signal can still be eavesdropped over a large area. For
example a typical parabolic antenna has a beam width of 16, at 1.4km one would still be
able to receive the signal 194 meters on either side of where it is pointing. The signal can also
be listened to behind the intended location. With a free space network you must intercept the
light beam, this is much more difficult and can be detected.
2. Interference
Radio waves can interfere with each other. This interference is one of the reasons the FCC
licenses spectrum. There are blocks of spectrum free to use, but other devices are also using
them. As an example if you used the public block in the 2.4GHz range, your signal can get
interference from portable phones, wireless access points, microwave ovens, car alarms, and
security cameras. This can make your signal less dependable.
Free space optic networks are free from these types of interference.
3. Distance
Radio waves have improved distance over free space optics. Free space optics is limited to
how far it can travel through the atmosphere because of absorption.
4. Fresnel Zones
The Fresnel zone of light is very small compared to radio waves. If there is an obstruction in
the first Fresnel zone it will produce interference.
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Optics
Geometric:
The RONJA uses a double convex spherical lens, which is typical found in magnifying
glasses. As shown in Figure 2, the RONJA uses the lens to take light from a LED and
collimate it, as well as take incoming light into a point.
The Transmitter side takes light from a LED and it will collimate it towards the Receiver
side.
The Receiver will take incoming parallel light and will focus it into a point using a double
Convex Lens.
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Signals
Information in a computer is stored as a set of hi/lo values or binary. For example, an ASCII
a is represented as 01100001. This can be communicated as two sets of different voltages,
or like in the RONJA blink on and blink off. There are many ways to encode the information
to make it more resistant to noise or to make sure that timings are synchronized. The next
subsections go over some of the encodings used in Ethernet 10BASE-T and 100BASE-TX.
The RONJA currently supports 10BASE-T.
NRZ Encoding
NRZ (Non-Return to Zero) is a simple encoding, hi for 1 and lo for 0, each bit delimited by
time (See Figure 6). In NRZ, clock timing is important and is often used internally when
everything is operating off the same clock. Imagine a long stream of 1s there would not be
any indication of how to set your clock between bits. If this information is sent to another
system that has a slightly different clock, it could easily become out of sync.
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Manchester Encoding
An Ethernet 10Base-T network sends its data in a Manchester encoding. A property of the
Manchester encoding is that it needs twice the bandwidth of the data com-pared to NRZ, thus
a response capable of 10 MHz is needed (1 Hz/bit). Our LED and photo diode are capable of
handling these response times.
Encoding a Data Byte:
Encoding is the process of adding the correct transitions to the message signal in relation to
the data that is to be sent over the communication system. The first step is to establish the
data rate that is going to be used. Once this is fixed, then the mid-bit time can be determinedas of the data rate period. In our example we are going to use a data rate of 4 kHz. This
provides a bit period of 1/f = 1/4000 = 0.00025s or 250 s. Dividing by two gives us the mid-
bit time (which we will label T) of 125 s. Now let's look at how we use this to encode a
data byte of 0xC5 (11000101b). The easiest method to do this is to use a timer set to expire or
interrupt at the T interval. We also need to set up a method to track which bit period we are
currently sending. Once we do this, we can easily encode the data and output the message
signal.
1. Begin with the output signal high.
2. Check if all bits have been sent, If yes, then go to step 7
3. Check the next logical bit to be coded
4. If the bit equals 1, then call ManchesterOne(T)
5. Else call ManchesterZero(T)
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6. Return to step 2
7. Set output signal high and return
Implementation of ManchesterOne(T)
1. Set the output signal low
2. Wait for mid-bit time (T)
3. Set the output signal high
4. Wait for mid-bit time (T)
5. Return
Implementation of ManchesterZero(T)
6. Set the output signal high
7. Wait for mid-bit time (T)
8. Set the output signal low
9. Wait for mid-bit time (T)
10. Return
These easy routines will provide an output at the microcontroller pin that exactly encodes the
data into a Manchester message signal at the desired data rate. The accuracy of the data rate
and duty cycle depends on the accuracy of the clock source and the method used to create the
wait times.
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Manchester Decoding
Decoding is where most people attempting to work with Manchester have questions. There
are several ways to approach this and each has unique benefits. This section will describe
how to implement two different methods. To start we will look at the steps that are needed for
either methodology.
1. The data rate clock must be either known or discovered (we will assume a known value)
2. We must synchronize to the clock (distinguish a bit edge from a mid-bit transition)
3. Process the incoming stream and recover the data using the previous two steps.
4. Buffer or store this data for further processing.
This provides the basic outline for how we will perform Manchester decoding. All that
remains is to implement this in software. As mentioned, we have two different options for
consideration.
One is based on timing while the other utilizes sampling.
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Timing Based Manchester Decode
In this approach we will capture the time between each transition coming from the
demodulation circuit. The Input Capture function on a micro-controller is very useful for this
because it will generate an interrupt, precise time measurements, and allow decision
processing based on the elapsed counter value.
1. Set up timer to interrupt on every edge (may require changing edge trigger in the ISR)
2. ISR routine should flag the edge occurred and store count value
3. Start timer, capture first edge and discard this.
4. Capture next edge and check if stored count value equal 2T (T = data rate)
5. Repeat step 4 until count value = 2T (This is now synchronized with the data clock)
6. Read current logic level of the incoming pin and save as current bit value (1 or 0)
7. Capture next edge
a. Compare stored count value with T
b. If value = T
i. Capture next edge and make sure this value also = T (else error)
ii. Next bit = current bit
iii. Return next bit
c. Else if value = 2T
i. Next bit = opposite of current bit
ii. Return next bit
d. Else
i. Return error
8. Store next bit in buffer
9. If desired number of bits are decoded; exit to continue further processing
10. Else set current bit to next bit and loop to step 7
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MLT-3(multi-level transmit)
MLT-3 is a encoding used in Ethernet 100BASE-TX. It changes from its current state to the
next every time there is a high. It has 3 states: typically positive, zero, and negative. A reason
to use this encoding is to reduce the frequency by four (one cycle: hi-med-lo-med) compared
to something like Manchester. This makes it easy to be transferred in copper cable. It reduces
the frequency traveling through copper cable for the 100BASE-TX to 31.25 MHz. This is of
no help in reducing the frequency when you have only two states on and off. Creating a third
state with the LED alone (such as half intensity), would reduce the range.
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BiPhase
BiPhase adds a level of complexity to the coding process but in return includes a way to
transfer the bit frame data clock that can be used in the decoding to increase accuracy.
BiPhase coding says that there will be a state transition in the message signal at the end of
every bit frame. In addition, a logical 1 will have an additional transition at the mid-bit.
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Modulation
Modulation refers to the act of adding the message signal to some form of carrier. The carrier,
by definition, is a higher frequency signal whose phase, frequency, amplitude, or some
combination thereof, is varied proportionally to the message. This change can be detected and
recovered (demodulated) at the other end of the communication channel. There are a number
of ways this can be done but for simplicity we will only look at Amplitude Modulation (AM),
On-Off Keying (a variation on AM), and Frequency Modulation (FM). Modulation is
typically carried out in hardware.
Amplitude Modulation
In amplitude modulation, the amplitude of the carrier is changed to follow the message
signal. In this case we can see a ripple on the carrier, its envelope contains the message.
This can be demodulated using an extremely simple envelope detector that captures this
ripple as a low frequency response.
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On-Off Keying
This form of modulation takes the amplitude modulation as described above to the extreme.
In this instance, we have only two states: Carrier and No Carrier. This approach lends itself
nicely to the transmission of digital data because the carrier can be simply switched on or
off depending on the state of the data being sent. The demodulated output is either high or
low depending on the presence of the carrier.
Frequency Modulation
Frequency modulation is more complicated but provides the benefit of constant output power
independent of the message being sent. With this approach, the frequency of the carrier is not
constant but varies in relation to the message. This requires a much more complicated
demodulation circuit typically implemented using a Phase Lock Loop (PLL).
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LED vs LASER
A common response to those introduced to the RONJA is that a LASER should be used
instead of a LED. This section will try to compare a LASER vs LED.
1 Response Time
The LASER has an advantage of shorter response times than the LED. The LASER diode is
stimulated to emit instead of spontaneous like the LED. LASER diodes with less than 1ns
(1Ghz) response times are available. It is hard to find diodes with less than 20ns (50Mhz)
response times. The LED response time works fine for the RONJA(10Mhz), if we wanted to
make a faster link, this is where the LASER could have an advantage.
2 Monochromatic
A LASER tends to emit a beam more monochromatic ( 24nm
FWHM), it makes it easier to add filters to the optics to only allow the light from the LASER
wavelength reducing ambient noise, and possibility of photo diode saturation from outside
sources. There are also disadvantages, because of the narrow wavelengths emitted by the
laser there could be conditions where that wavelength is absorbed, such as certain ice crystals
in the air that absorb certain narrow bands of wavelength. With the LED you are emitting a
much broader set of wavelengths. If some of it gets absorbed, you still have the rest to fall
back on.
3 Scintillation
Scintillation can be far worse for a LASER than the LED because the LASER is more
coherent than the LED. As the beam travels through the air, it will hit packets of air of
different temperature which have adifferent index of refraction causing constructive and
destructive interference which can ruin your signal. This effect can be especially bad
depending on the terrain it travels over. Asphalt, ponds, fountains, all create temperature
differences that will contribute to scintillation.
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4 Safety
LASERs can be dangerous. Devices sold to the market place that contain lasers must go
through the FDA. Even low powered lasers should have extra safety precautions such as auto
shutoff if there is a beam break. For lasers rated higher than IIIa/3R protective eye goggles
are needed when working with them. Even light reflected after it has hit a object can be
enough to damage the eye depending on the power and wavelength of the LASER.
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SYSTEM DEVELOPMENT
General Scrutiny
One Ronja device is a single long-distance optical transceiver that is capable of runningagainst the same or compatible device on the other side of the link. The topology is point-to-
point.
Building a Ronja is rather lenghty job (this will hopefully change in future) that however
pays off in a reliable and performant device that is capable of delivering steady connectivity
with little maintenance and can be run freely without a need of authorities' approval. Also a
possibility of interference and eavesdropping is negligible. Dropouts are infrequent and
determined solely by weather and are thus foreseeable.
He who wants to enjoy the adrenaline sport of driving primitive retail parts into flawless
cooperation to provide the uncurbed full duplex connectivity experience must withstand these
nuisances:
Ronja is somewhat labor expensive. Things have been made much easier by putting
the most complicated electronics on a PCB. The cost of parts is negligible in
comparison with the labor, for example the components for the whole Ronja 10M
Metropolis cost just 1500CZK. Further reduction in labor demands is planned by
putting RX and TX on PCB too.
The user must possess certain basic manual skills as soldering, drilling, painting, and
technical drawing/schematic reading. But people without any previous experience
with soldering have built a piece that worked on the first try!
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The user must not cut the corners during the building
Butthere are also certain conveniences:
The parts are chosen to be of the widest availability possible and equivalents are
provided where applicable
Innovative approach is used to speed up the work and make it convenient. Sector
codes are present to make the population easy. Drilling is simplified by drilling
templates - just print and no measurement is necessary in the workshop!
The device is based on the KISS rule (Keep It Simple, Stupid) which makes the
device plug-and-play immediately after the building provided the user hasn't botched
anything.
The design is rugged and over dimensioned to withstand variations in the
components. As a consequence, the resulting device is rock solid in steady
performance and provides outstanding electromagnetic interference immunity and
electromagnetic compatibility. Withstands -20C as well as direct sunlight and heat
with obvious margin. During a lightning storm, lightning strike in proximity usually
doesn't generate even a single lost bit.
In case of device failure (direct lightning strike), the measuring points can be
inspected and bad components replaced without a need to throw the whole device out.
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gates. Therefore the 74AC04 is operating as a structured powerCMOSswitch completely in
analog mode.
This way the LEDjunctionis flooded and cleared ofcarriersas quickly as possible, basically
byshort circuitdischarge. This pushes the speed of the LED to maximum, which makes the
output optical signal fast enough so that the range/power ratio is the same as with the faster
red HPWT-BD00-F4000 LED. The side effects of this brutal driving technique are: 1) the
LED overshoots at the beginning of longer (5 MHz/1 MHz) impulses to about 2x brightness.
This was measured to have no adverse effect on range. 2) A blockingceramic capacitorbank
backing up the 74AC04 switching array is crucial for correct operation, because charging and
discharging the LED is done by short circuit. Under dimensioning this bank causes the
leading and trailing edges of the optical output to grow longer.
http://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/CMOShttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Ceramic_capacitorhttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Charge_carrierhttp://en.wikipedia.org/wiki/Semiconductor_junctionhttp://en.wikipedia.org/wiki/CMOS -
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Optical Receiver - Preamplifier stage:
The usual approach in FSO (Free Space Optics)preamplifiersis to employ atransimpedance
amplifier.A transimpedance amplifier is a very sensitivebroadbandhigh-speed device
featuring afeedback loop.
Following is the brief scrutiny of a transimpedance amplifier:
The transimpedance amplifier as shown above presents a low impedance to the photodiode
and isolates it from the output voltage of the operational amplifier. In its simplest form a
transimpedance amplifier has just a large valued feedback resistor, Rf. The gain of the
amplifer is set by this resistor and because the amplifier is in an inverting configuration, has a
value of -Rf. There are several different configurations of transimpedance amplifiers, each
suited to a particular application. The one factor they all have in common is the requirement
to convert the low-level current of a sensor to a voltage. The gain, bandwidth, as well as
current and voltage offsets change with different types of sensors, requiring different
configurations of transimpedance amplifiers.
This transimpedance amplifier inside a ronja system also makes use of a PIN diode.
A PIN diode is adiode with a wide, undopedintrinsic semiconductor region between ap-type
semiconductor and ann-type semiconductor region. The p-type and n-type regions are
typically heavilydopedbecause they are used forohmic contacts.A PIN diode operates
under what is known as high-level injection. In other words, the intrinsic "i" region is flooded
with charge carriers from the "p" and "n" regions.
http://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Preamplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Intrinsic_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/N-type_semiconductorhttp://en.wikipedia.org/wiki/Doping_%28semiconductor%29http://en.wikipedia.org/wiki/Ohmic_contacthttp://en.wikipedia.org/wiki/Ohmic_contacthttp://en.wikipedia.org/wiki/Doping_%28semiconductor%29http://en.wikipedia.org/wiki/N-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/P-type_semiconductorhttp://en.wikipedia.org/wiki/Intrinsic_semiconductorhttp://en.wikipedia.org/wiki/Diodehttp://en.wikipedia.org/wiki/Feedback_loophttp://en.wikipedia.org/wiki/Broadbandhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Transimpedance_amplifierhttp://en.wikipedia.org/wiki/Preamplifier -
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Its function can be likened to filling up a water bucket with a hole on the side. Once the water
reaches the hole's level it will begin to pour out. Similarly, the diode will conduct current
once the flooded electrons and holes reach an equilibrium point, where the number of
electrons is equal to the number of holes in the intrinsic region. When the diode is forward
biased, the injected carrier concentration is typically several orders of magnitude higher than
the intrinsic level carrier concentration. Due to this high level injection, which in turn is due
to thedepletion process,the electric field extends deeply (almost the entire length) into the
region. This electric field helps in speeding up of the transport of charge carriers from P to N
region, which results in faster operation of the diode, making it a suitable device for high
frequency operations.
Ronja however uses a feedback-less design where the PIN has a high workingelectrical
resistance(100kilohms)which together with the total input capacitance (roughly 7 pF, 5 pF
PIN and 2 pF inputMOSFETcascade)makes the device operate with apassbandon a 6
dB/oct slope of low pass formed by PIN working resistance and total input capacitance. The
signal is then immediately amplified to remove the danger of contamination bysignal noise,
and then a compensation of the 6 dB/oct slope is done by derivator element on the
programming pins of an NE592 video amplifier. The NE592 video amplifier is a monolithic,
two-stage, differential output, and wideband video amplifier. It offers fixed gains of 100 and
400 without external components and adjustable gains from 400 to 0 with one external
resistor. The input stage is designed so that with the addition of a few external reactive
elements between the gain select terminals, the circuit can function as a high-pass, low-pass,
or band-pass filter.
http://en.wikipedia.org/wiki/Depletion_regionhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Signal_noisehttp://en.wikipedia.org/wiki/Passbandhttp://en.wikipedia.org/wiki/Cascodehttp://en.wikipedia.org/wiki/MOSFEThttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Depletion_region -
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This feature makes the circuit ideal for use as a video or pulse amplifier in
communications, magnetic memories, display, video recorder systems, and floppy
disk head amplifiers. It is available in an 8-pin version with fixed gain of 400 without
external components and adjustable gain from 400 to 0 with one external resistor.
Due to this implementation, a surprisingly flat characteristic is obtained in the
receiver section of the RONJA. If the PIN diode is equipped with 3 kworking
resistor to operate in flat band mode, the range is reduced to about 30% due tothermal
noisefrom the 3 k resistor.
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Transceiver - Ronja Twister:
An optical transceiver module configured for long wave optical transmission is disclosed.
Significantly, the transceiver module utilizes components formerly used only for shortwave
optical transmission, thereby reducing new component production and device complexity. Inone embodiment, the transceiver module includes a transmitter optical subassembly including
a laser capable of producing an optical signal. A consolidated laser driver/post amplifier
including a first bias current source provides a bias current to the laser for producing the
optical signal. A means for amplifying the bias current provided to the laser by the first bias
current source is also included as a separate component from the laser driver/post amplifier.
The means for amplifying in one embodiment is a field-effect transistor that is operably
connected to the laser driver/post amplifier and configured to provide an additional bias
current to the laser diode such that sufficient lasing operation of the laser is realized.
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Physical Layer:
In the seven-layerOpen Systems Interconnection model (OSI) ofcomputer networking,the
physical layer or layer 1 is the first (lowest) layer. The implementation of this layer is often
termed PHY. The physical layer consists of the basicnetworking hardware transmission
technologies of anetwork.It is a fundamental layer underlying the logical data structures of
the higher level functions in a network. Due to the plethora of available hardware
technologies with widely varying characteristics, this is perhaps the most complex layer in
the OSI architecture. The physical layer defines the means of transmitting raw bits rather than
logicaldata packets over a physicallink connectingnetwork nodes.Thebit stream may be
grouped into code words or symbols and converted to a physicalsignal that is transmitted
over a hardwaretransmission medium.The physical layer provides an electrical, mechanical,and procedural interface to the transmission medium.
The major functions and services performed by the physical layer are:
Bit-by-bit orsymbol-by-symbol delivery
Providing a standardized interface to physicaltransmission media,including
Mechanical specification ofelectrical connectors andcables,for example maximum
cable length
Electrical specification oftransmission linesignal level andimpedance
Radio interface, includingelectromagnetic spectrumfrequency allocation and
specification ofsignal strength,analogbandwidth,etc.
http://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Networking_hardwarehttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Network_packethttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Network_nodehttp://en.wikipedia.org/wiki/Bit_streamhttp://en.wikipedia.org/wiki/Signal_%28electronics%29http://en.wikipedia.org/wiki/Transmission_mediumhttp://en.wikipedia.org/wiki/Symbol_%28data%29http://en.wikipedia.org/wiki/Transmission_mediahttp://en.wikipedia.org/wiki/Electrical_connectorhttp://en.wikipedia.org/wiki/Cablehttp://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Signal_levelhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Signal_strengthhttp://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Signal_strengthhttp://en.wikipedia.org/wiki/Frequency_allocationhttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Signal_levelhttp://en.wikipedia.org/wiki/Transmission_linehttp://en.wikipedia.org/wiki/Cablehttp://en.wikipedia.org/wiki/Electrical_connectorhttp://en.wikipedia.org/wiki/Transmission_mediahttp://en.wikipedia.org/wiki/Symbol_%28data%29http://en.wikipedia.org/wiki/Transmission_mediumhttp://en.wikipedia.org/wiki/Signal_%28electronics%29http://en.wikipedia.org/wiki/Bit_streamhttp://en.wikipedia.org/wiki/Network_nodehttp://en.wikipedia.org/wiki/Data_linkhttp://en.wikipedia.org/wiki/Network_packethttp://en.wikipedia.org/wiki/Computer_networkhttp://en.wikipedia.org/wiki/Networking_hardwarehttp://en.wikipedia.org/wiki/Computer_network -
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Specifications forIR overoptical fiber or a wireless IR communication link
Modulation
Line coding
Bit synchronization in synchronousserial communication
Start-stop signaling andflow control inasynchronous serial communication
Circuit switching
Multiplexing
Establishment and termination ofcircuit switched connections
Carrier sense andcollision detection utilized by some level 2multiple access
protocols
Equalization filtering,training sequences,pulse shaping and othersignal processing
of physical signals
Forward error correction for example bitwise convolutional coding
Bit-interleaving and otherchannel coding
http://en.wikipedia.org/wiki/Infrared_radiationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Line_codinghttp://en.wikipedia.org/wiki/Bit_synchronizationhttp://en.wikipedia.org/wiki/Serial_communicationhttp://en.wikipedia.org/wiki/Start-stop_signallinghttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Asynchronous_serial_communicationhttp://en.wikipedia.org/wiki/Circuit_switchinghttp://en.wikipedia.org/wiki/Multiplexinghttp://en.wikipedia.org/wiki/Circuit_switchedhttp://en.wikipedia.org/wiki/Carrier_sensehttp://en.wikipedia.org/wiki/CSMA/CDhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Equalizationhttp://en.wikipedia.org/wiki/Training_sequencehttp://en.wikipedia.org/wiki/Pulse_shapinghttp://en.wikipedia.org/wiki/Signal_processinghttp://en.wikipedia.org/wiki/Forward_error_correctionhttp://en.wikipedia.org/wiki/Bit-interleavinghttp://en.wikipedia.org/wiki/Channel_codinghttp://en.wikipedia.org/wiki/Channel_codinghttp://en.wikipedia.org/wiki/Bit-interleavinghttp://en.wikipedia.org/wiki/Forward_error_correctionhttp://en.wikipedia.org/wiki/Signal_processinghttp://en.wikipedia.org/wiki/Pulse_shapinghttp://en.wikipedia.org/wiki/Training_sequencehttp://en.wikipedia.org/wiki/Equalizationhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/Multiple_access_protocolhttp://en.wikipedia.org/wiki/CSMA/CDhttp://en.wikipedia.org/wiki/Carrier_sensehttp://en.wikipedia.org/wiki/Circuit_switchedhttp://en.wikipedia.org/wiki/Multiplexinghttp://en.wikipedia.org/wiki/Circuit_switchinghttp://en.wikipedia.org/wiki/Asynchronous_serial_communicationhttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Start-stop_signallinghttp://en.wikipedia.org/wiki/Serial_communicationhttp://en.wikipedia.org/wiki/Bit_synchronizationhttp://en.wikipedia.org/wiki/Line_codinghttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Infrared_radiation -
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Data link layer:
The data link layer is the protocol layer that transfers data between adjacent network nodes in
wide area network or between nodes on the samelocal area networksegment.The data link
layer provides the functional and procedural means totransfer data between network entities
and might provide the means to detect and possibly correct errors that may occur in the layer.
Examples of data link protocols areEthernet for local area networks (multi-node), thePoint-
to-Point Protocol (PPP),HDLC andADCCP for point-to-point (dual-node) connections. The
data link layer is concerned with local delivery offramesbetween devices on the same LAN.
Data-link frames, as theseprotocol data units are called, do not cross the boundaries of a local
network. Inter-network routing and global addressing are higher layer functions, allowing
data-link protocols to focus on local delivery, addressing, and media arbitration. In this way,
the data link layer is analogous to a neighborhood traffic copy; it endeavors to arbitrate
between parties contending for access to a medium, without concern for their ultimate
destination. When devices attempt to use a medium simultaneously, frame collisions occur.
Data-link protocols specify how devices detect and recover from such collisions, and may
provide mechanisms to reduce or prevent them.
Delivery of frames by layer 2 devices is effected through the use of unambiguous hardware
addresses. A frame's header contains source and destination addresses that indicate which
device originated the frame and which device is expected to receive and process it. In contrast
to the hierarchical and routable addresses of the network layer, layer-2 addresses are flat,
meaning that no part of the address can be used to identify the logical or physical group to
which the address belongs.
The data link thus provides data transfer across the physical link. That transfer can be reliable
or unreliable; many data-link protocols do not have acknowledgments of successfulframe
reception and acceptance, and some data-link protocols might not even have any form of
checksum to check for transmission errors. In those cases, higher-level protocols must
provideflow control,error checking, and acknowledgments and retransmission.
In some networks, such asIEEE 802 local area networks, the data link layer is described in
more detail withmedia access control (MAC) andlogical link control (LLC) sub layers; this
means that theIEEE 802.2 LLC protocol can be used with all of the IEEE 802 MAC layers,
such as Ethernet,token ring,IEEE 802.11,etc., as well as with some non-802 MAC layers
such asFDDI.Other data-link-layer protocols, such asHDLC,are specified to include both
sub layers, although some other protocols, such asCisco HDLC,use HDLC's low-level
framing as a MAC layer in combination with a different LLC layer. In theITU-TG.hn
http://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Network_segmenthttp://en.wikipedia.org/wiki/Transfer_%28computing%29http://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/ADCCPhttp://en.wikipedia.org/wiki/Frame_%28networking%29http://en.wikipedia.org/wiki/Protocol_data_unitshttp://en.wikipedia.org/wiki/Data_framehttp://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/IEEE_802http://en.wikipedia.org/wiki/Media_access_controlhttp://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/IEEE_802.2http://en.wikipedia.org/wiki/Token_ringhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/FDDIhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/Cisco_HDLChttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/Cisco_HDLChttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/FDDIhttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Token_ringhttp://en.wikipedia.org/wiki/IEEE_802.2http://en.wikipedia.org/wiki/Logical_link_controlhttp://en.wikipedia.org/wiki/Media_access_controlhttp://en.wikipedia.org/wiki/IEEE_802http://en.wikipedia.org/wiki/Flow_control_%28data%29http://en.wikipedia.org/wiki/Data_framehttp://en.wikipedia.org/wiki/Protocol_data_unitshttp://en.wikipedia.org/wiki/Frame_%28networking%29http://en.wikipedia.org/wiki/ADCCPhttp://en.wikipedia.org/wiki/HDLChttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Point-to-Point_Protocolhttp://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Transfer_%28computing%29http://en.wikipedia.org/wiki/Network_segmenthttp://en.wikipedia.org/wiki/Local_area_networkhttp://en.wikipedia.org/wiki/Wide_area_network -
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MODELS
Ronja Tetrapolis: Range of 1.4 km (0.87 mi), red visible light. Connect
with8P8Cconnector into anetwork cardor switch.
Ronja 10M Metropolis: Range of 1.4 km (0.87 mi), red visible light. Connects
toAttachment Unit Interface.
Ronja Inferno: Range of 1.25 km (0.78 mi), invisible infrared light.
Ronja Bench-press: A measurement device for developers for physical measurement of
lens/LED combination gain and calculation of range from that
Ronja Tetrapolis:
Ronja Tetrapolis is a device for optical communication with 10Mbps full duplex speed over
1.4km. The device terminates an optical path. To operate a complete link, two devices are
necessary.
Ronja Benchpress:
This is a Ronja model that is not a communication device, but a bench for measuring lens
properties. You insert a combination of LED and lens into the bench and measure exact
transmitter gain of the lens+LED combination in decibels. You can then use this value to
calculate precise range of the device. This is handy for evaluating new types of LEDs, new
types of lenses or if you have doubts if your lens is of adequate quality for the device (for
example due to greenish haze).
Ronja 10M Metropolis:
This is another variant of Ronja similar to Ronja Tetropolis, but varying in its technical
specifications.
Ronja Inferno:
Ronja Inferno is a device for optical communication with 10Mbps full duplex speed over
1.25 km using infraredlight. The device terminates an optical path. To operate a complete
link, two devices are necessary
http://en.wikipedia.org/wiki/8P8Chttp://en.wikipedia.org/wiki/8P8Chttp://en.wikipedia.org/wiki/8P8Chttp://en.wikipedia.org/wiki/Network_cardhttp://en.wikipedia.org/wiki/Network_cardhttp://en.wikipedia.org/wiki/Network_cardhttp://en.wikipedia.org/wiki/Attachment_Unit_Interfacehttp://en.wikipedia.org/wiki/Attachment_Unit_Interfacehttp://en.wikipedia.org/wiki/Attachment_Unit_Interfacehttp://en.wikipedia.org/wiki/Attachment_Unit_Interfacehttp://en.wikipedia.org/wiki/Network_cardhttp://en.wikipedia.org/wiki/8P8C -
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Technical specifications:
Ronja Inferno:
Gross data rate 10 Mbps
Transmission
modeFull duplex (half duplex also supported)
Nominal range1.25 km with 130mm RX loupe lenses and 90mm TX loupe lenses. The switch or cad has
to havewell implemented PLL.
Minimum
operating distance
1/4 of nominal range. Further manual reduction possible by change of two passive
components in receiver.
Data interface
Connects with RJ45 jack into IEEE 802.3 UTP interface. Must be plugged
directly into data terminal equipment (DTE, PC or a switch) using the integral
1m cable. Auto negotiation not supported, not transparent for auto negotiation
signals.
The preamble is chopped off more than specified by IEEE 802.3 which could
cause a problem when Ronja is connected into a cascade of pure hubs. However
hubs almost don't exist today anymore so it is not a problem.
Doesn't comply to IEEE 802.3 regarding not transmitting when link integrity is
not yet established. This violates page 303 14.2 g) - but IEEE 802.3 compliantdevices must work with it. Complying to it would make Ronja Tetrapolis more
complicated
Power
consumption
335mA @12VDC (4.02W) from wall cube, 2W from external heating power supply
(switchable off).
Typical Maximum
Idle 225mA 285mA
Full data load (both directions) 275mA 335mA
Operating
wavelengthInfrared, 875nm wavelength, 37nm spectral width
Optical output 30mW
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Ronja Tetrapolis:
Gross data rate 10 Mbps
Transmission
modeFull duplex (half duplex also supported)
Nominal range 1.4km with 130mm lenses. The switch or cad has to havewell implemented PLL.
Minimum
operating distance
1/4 of nominal range. Further manual reduction possible by change of two passive
components in receiver.
Data interface
Connects with RJ45 jack into IEEE 802.3 UTP interface. Must be plugged directly
into data terminal equipment (DTE, PC or a switch) using the integral 1m cable.
Auto negotiation not supported, not transparent for auto negotiation signals.
The preamble is chopped off more than specified by IEEE 802.3 which could cause
a problem when Ronja is connected into a cascade of pure hubs. However hubs
almost don't exist today anymore so it is not a problem.
Doesn't comply with IEEE 802.3 regarding not transmitting when link integrity is
not yet established. This violates page 303 14.2 g) - but IEEE 802.3 compliant
devices must work with it. Complying to it would make Ronja Tetrapolis more
complicated
Power
consumption
285mA @12VDC (3.42W) from wall cube, 2W from external heating power supply
(switchable off).
Typical Maximum
Idle 185mA 245mA
Full data load (both directions) 225mA 285mA
Operating
wavelengthvisible, 625nm, 100nm spectral width (618nm perceived wavelength, red-orange)
Optical output 17.2mW
Divergence cone
half angle1.9mrad (130mm aperture transmitter lens)
Estimated Optical
EIRP
20kW (130mm aperture transmitter lens, HPWT-BD00-F4000)
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Operating
temperature-30...+70degC (outdoor part - optical heads, RX, TX), 0...+55degC (indoor part - Twister2)
Operating
humidity
Up to 100% (condensing) with lens heating on (outdoor part), up to 95% with lens heating
off (and indoor electronics).
Weight 15.5kg (one side of a link, on a welded parallel console)
Required visibility 4km at maximum range.
Optical
modulation
BPSK (as on AUI aka Manchester) plus 1MHz asynchronous 50% duty cycle square wave
between packets. The transmitter appears to shine permanently and steadily no matter if data
pass or not.
Indicators LEDs Power, Receive Packet, Transmit Packet
Aiming systemVisual, retro reflector for transmitter and DC voltage signal strength monitor port for
receiver.
Mechanical
Installation
Constraints
Possible mount places:
PlaceIs drilling
necessary?
Railing, round or rectangular No
Wall Yes
Corner of wall Yes
Chimney No
Horizontal or tilted surface of masonry or
masonry covered with tin, foil etc.Yes
Ceiling Yes
Max. 1m from RJ45 connector is a grounded metal box with dimensions
180x123x62 mm.
Cable distance between RJ45 connector and optical head mounting points is max.
100m
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Ronja Benchpress:
Operating ambient temperature 0+55C
Usage environment Indoor
Operating humidity 0-95% noncondensing
Ronja 10M Metropolis:
Gross data rate 10 Mbps
Transmissionmode
Full duplex only
Nominal range1.4km with HPWT-BD00-F4000 and 130mm lenses. The switch or cad has to havewell
implemented PLL.
Minimum
operating
distance
1/4 of nominal range. Further manual reduction possible by change of two passive
components in receiver.
Data interface
IEEE 802.3 Attachment Unit Interface (AUI). Connector male DB-15 with screws instead of
AUI mechanical latch. AUI cable not supported - integrated cable length 1m. The preamble is
chopped off more than specified by IEEE 802.3 which could cause a problem when Ronja is
connected into a cascade of pure hubs. However hubs almost don't exist today anymore so it is
not a problem.
Power
consumption300mA @12VDC (3.6W) from AUI, 2W from external heating power supply (switchable off)
Operating
wavelengthvisible, 625nm, 100nm spectral width (618nm perceived wavelength, red-orange)
Optical output 17.2mW
Divergence
cone half angle1.9mrad (130mm aperture transmitter lens)
Estimated
Optical EIRP
20kW (130mm aperture transmitter lens, HPWT-BD00-F4000)
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Operating
temperature-30+70C (outdoor part - optical heads, RX, TX), 0+55C (indoor part - AUI interface)
Operating
humidity
Up to 100% (condensing) with lens heating on, up to 95% with lens heating off.
Weight 15.5kg (one side of a link, on a welded parallel console)
Required
visibility4km for uninterrupted operation at full range.
Optical
modulation
BPSK (as on AUI) plus 1MHz asynchronous 50% duty cycle square wave between packets.
The transmitter appears to shine permanently and steadily no matter if data pass or not.
Indicators LEDs Power, Receive Packet, Transmit Packet
CONCLUSION
The Twibright Ronja datalink thus, can network neighbouring houses with cross-street
ethernet access, solve the last mile problem for ISPs, or provide a link layer for fast
neighbourhood mesh networks.
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Our LED has a max response of 20ns (50 MHz). So we would run into a problem if we
wanted to increase the speed to 100Mbits/s by transmitting in a similar manner with the LED.
There are a few solutions. We could use a LASER which has much faster response rates than
LEDs and read in the MLT-3 and transmit NRZ at max frequency of 62.5 MHz, with the
receiver converting NRZ back to MLT-3. We can also communicate in parallel instead of
serial, we would require several transmitters and receivers. For example if we had three
transmitters/receivers then each transmitter could handle a maximum frequency of 21Mhz.
Using multiple transmitters/receivers brings up several issues: noise from other transmitters,
4B5B would not guarantee a hi-lo transition for each detector, mounting space issues. One
thing is certain making a 100Mbit/s network would be easy.
PROS AND CONS
Pros:
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1) The parts were chosen to be of the widest availability possible and equivalents are
provided where applicable.
2)
Innovative approach is used to speed up the work and make it convenient. Sector
codes are present to make the population easy. Drilling is simplified by drilling
templates - just print and no measurement is necessary in the workshop!
3)
Withstands -20C as well as direct sunlight and heat with obvious margin. During a
lightning storm, lightning strike in proximity usually doesn't generate even a single
lost bit.
4) In case of device failure (direct lightning strike), the measuring points can be
inspected and bad components replaced without a need to throw the whole device out.
Cons:
1) Ronja is somewhat labor expensive. Things have been made much easier by putting
the most complicated electronics on a PCB. The cost of parts is negligible in
comparison with the labor, for example the components for the whole Ronja 10M
Metropolis cost just 1500CZK. Further reduction in labor demands is planned by
putting RX and TX on PCB too.
2)
The user must possess certain basic manual skills as soldering, drilling, painting, and
technical drawing/schematic reading. But people without any previous experience
with soldering have built a piece that worked on the first try!
3)
The user must not cut the corners during the building.
REFERENCES
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Twibright Labs. Ronja. .
Kenneth Krane. Modern Physics Second Edition. John Wiley &
Sons, Inc.
www.wikipedia.org
Twibright Labs. Making Ronja on short tracks.
.
http://www.wikipedia.org/http://www.wikipedia.org/http://www.wikipedia.org/